Normalize indices on init

excalidraw-app/App.tsx

@@ -26,6 +26,7 @@ import {
   TTDDialogTrigger,
   StoreAction,
   reconcileElements,
+  normalizeIndices,
 } from "../packages/excalidraw";
 import type {
   AppState,
@@ -305,14 +306,21 @@ const initializeScene = async (opts: {
       key: roomLinkData.roomKey,
     };
   } else if (scene) {
+    const normalizedScene = {
+      ...scene,
+      // non-collab scenes are always always normalized on init
+      // collab scenes are normalized only on "first-in-room" as part of collabAPI
+      elements: normalizeIndices(scene.elements),
+    };
+
     return isExternalScene && jsonBackendMatch
       ? {
-          scene,
+          scene: normalizedScene,
           isExternalScene,
           id: jsonBackendMatch[1],
           key: jsonBackendMatch[2],
         }
-      : { scene, isExternalScene: false };
+      : { scene: normalizedScene, isExternalScene: false };
   }
   return { scene: null, isExternalScene: false };
 };

excalidraw-app/collab/Collab.tsx

@@ -18,6 +18,7 @@ import {
   restoreElements,
   zoomToFitBounds,
   reconcileElements,
+  normalizeIndices,
 } from "../../packages/excalidraw";
 import type { Collaborator, Gesture } from "../../packages/excalidraw/types";
 import {
@@ -637,7 +638,16 @@ class Collab extends PureComponent<CollabProps, CollabState> {
         fetchScene: true,
         roomLinkData: existingRoomLinkData,
       });
-      scenePromise.resolve(sceneData);
+
+      if (sceneData) {
+        scenePromise.resolve({
+          ...sceneData,
+          // normalize fractional indices on init for shared scenes, while making sure there are no other collaborators
+          elements: normalizeIndices([...sceneData.elements]),
+        });
+      } else {
+        scenePromise.resolve(null);
+      }
     });
 
     this.portal.socket.on(

excalidraw-app/data/index.ts

@@ -254,7 +254,7 @@ export const loadScene = async (
       await importFromBackend(id, privateKey),
       localDataState?.appState,
       localDataState?.elements,
-      { repairBindings: true, refreshDimensions: false },
+      { repairBindings: true },
     );
   } else {
     data = restore(localDataState || null, null, null, {